<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
    <head>
        <!-- Book generated using mdBook -->
        <meta charset="UTF-8">
        <title>Create, Read, Update, Delete - WatermelonDB documentation</title>
        
        


        <!-- Custom HTML head -->
        


        <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
        <meta name="description" content="">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <meta name="theme-color" content="#ffffff" />

        
        <link rel="icon" href="favicon.svg">
        
        
        <link rel="shortcut icon" href="favicon.png">
        
        <link rel="stylesheet" href="css/variables.css">
        <link rel="stylesheet" href="css/general.css">
        <link rel="stylesheet" href="css/chrome.css">
        
        <link rel="stylesheet" href="css/print.css" media="print">
        

        <!-- Fonts -->
        <link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
        
        <link rel="stylesheet" href="fonts/fonts.css">
        

        <!-- Highlight.js Stylesheets -->
        <link rel="stylesheet" href="highlight.css">
        <link rel="stylesheet" href="tomorrow-night.css">
        <link rel="stylesheet" href="ayu-highlight.css">

        <!-- Custom theme stylesheets -->
        

        
    </head>
    <body>
        <!-- Provide site root to javascript -->
        <script type="text/javascript">
            var path_to_root = "";
            var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
        </script>

        <!-- Work around some values being stored in localStorage wrapped in quotes -->
        <script type="text/javascript">
            try {
                var theme = localStorage.getItem('mdbook-theme');
                var sidebar = localStorage.getItem('mdbook-sidebar');

                if (theme.startsWith('"') && theme.endsWith('"')) {
                    localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
                }

                if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
                    localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
                }
            } catch (e) { }
        </script>

        <!-- Set the theme before any content is loaded, prevents flash -->
        <script type="text/javascript">
            var theme;
            try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
            if (theme === null || theme === undefined) { theme = default_theme; }
            var html = document.querySelector('html');
            html.classList.remove('no-js')
            html.classList.remove('light')
            html.classList.add(theme);
            html.classList.add('js');
        </script>

        <!-- Hide / unhide sidebar before it is displayed -->
        <script type="text/javascript">
            var html = document.querySelector('html');
            var sidebar = 'hidden';
            if (document.body.clientWidth >= 1080) {
                try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
                sidebar = sidebar || 'visible';
            }
            html.classList.remove('sidebar-visible');
            html.classList.add("sidebar-" + sidebar);
        </script>

        <nav id="sidebar" class="sidebar" aria-label="Table of contents">
            <div class="sidebar-scrollbox">
                <ol class="chapter"><li class="chapter-item expanded "><a href="ch01-00-get-excited.html"><strong aria-hidden="true">1.</strong> Get excited</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="index.html"><strong aria-hidden="true">1.1.</strong> Check out the README</a></li><li class="chapter-item expanded "><a href="Demo.html"><strong aria-hidden="true">1.2.</strong> See the demo</a></li></ol></li><li class="chapter-item expanded "><a href="ch02-00-learn-to-use.html"><strong aria-hidden="true">2.</strong> Learn to use Watermelon</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="Installation.html"><strong aria-hidden="true">2.1.</strong> Installation</a></li><li class="chapter-item expanded "><a href="Setup.html"><strong aria-hidden="true">2.2.</strong> Setup</a></li><li class="chapter-item expanded "><a href="Schema.html"><strong aria-hidden="true">2.3.</strong> Schema</a></li><li class="chapter-item expanded "><a href="Model.html"><strong aria-hidden="true">2.4.</strong> Defining Models</a></li><li class="chapter-item expanded "><a href="CRUD.html" class="active"><strong aria-hidden="true">2.5.</strong> Create, Read, Update, Delete</a></li><li class="chapter-item expanded "><a href="Components.html"><strong aria-hidden="true">2.6.</strong> Connecting to React Components</a></li><li class="chapter-item expanded "><a href="Query.html"><strong aria-hidden="true">2.7.</strong> Querying</a></li><li class="chapter-item expanded "><a href="Relation.html"><strong aria-hidden="true">2.8.</strong> Relations</a></li><li class="chapter-item expanded "><a href="Actions.html"><strong aria-hidden="true">2.9.</strong> Custom Actions</a></li></ol></li><li class="chapter-item expanded "><a href="ch03-00-advanced.html"><strong aria-hidden="true">3.</strong> Advanced guides</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="Advanced/Migrations.html"><strong aria-hidden="true">3.1.</strong> Migrations</a></li><li class="chapter-item expanded "><a href="Advanced/Sync.html"><strong aria-hidden="true">3.2.</strong> Sync</a></li><li class="chapter-item expanded "><a href="Advanced/CreateUpdateTracking.html"><strong aria-hidden="true">3.3.</strong> Automatic create/update tracking</a></li><li class="chapter-item expanded "><a href="Advanced/AdvancedFields.html"><strong aria-hidden="true">3.4.</strong> Advanced fields</a></li><li class="chapter-item expanded "><a href="Advanced/Flow.html"><strong aria-hidden="true">3.5.</strong> Flow</a></li><li class="chapter-item expanded "><a href="Advanced/LocalStorage.html"><strong aria-hidden="true">3.6.</strong> LocalStorage</a></li><li class="chapter-item expanded "><a href="Advanced/ProTips.html"><strong aria-hidden="true">3.7.</strong> Pro tips</a></li><li class="chapter-item expanded "><a href="Advanced/Performance.html"><strong aria-hidden="true">3.8.</strong> Performance tips</a></li><li class="chapter-item expanded "><a href="Advanced/SharingDatabaseAcrossTargets.html"><strong aria-hidden="true">3.9.</strong> iOS - Sharing database across targets</a></li></ol></li><li class="chapter-item expanded "><a href="ch04-00-deeper.html"><strong aria-hidden="true">4.</strong> Dig deeper into WatermelonDB</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="Implementation/Architecture.html"><strong aria-hidden="true">4.1.</strong> Architecture</a></li><li class="chapter-item expanded "><a href="Implementation/Adapters.html"><strong aria-hidden="true">4.2.</strong> Adapters</a></li><li class="chapter-item expanded "><a href="Implementation/SyncImpl.html"><strong aria-hidden="true">4.3.</strong> Sync implementation</a></li></ol></li><li class="chapter-item expanded "><a href="ch04-00-deeper.html"><strong aria-hidden="true">5.</strong> Other</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="Roadmap.html"><strong aria-hidden="true">5.1.</strong> Roadmap</a></li><li class="chapter-item expanded "><a href="CONTRIBUTING.html"><strong aria-hidden="true">5.2.</strong> Contributing</a></li><li class="chapter-item expanded "><a href="CHANGELOG.html"><strong aria-hidden="true">5.3.</strong> Changelog</a></li></ol></li></ol>
            </div>
            <div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
        </nav>

        <div id="page-wrapper" class="page-wrapper">

            <div class="page">
                
                <div id="menu-bar-hover-placeholder"></div>
                <div id="menu-bar" class="menu-bar sticky bordered">
                    <div class="left-buttons">
                        <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
                            <i class="fa fa-bars"></i>
                        </button>
                        <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
                            <i class="fa fa-paint-brush"></i>
                        </button>
                        <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
                            <li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
                            <li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
                        </ul>
                        
                        <button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
                            <i class="fa fa-search"></i>
                        </button>
                        
                    </div>

                    <h1 class="menu-title">WatermelonDB documentation</h1>

                    <div class="right-buttons">
                        
                        <a href="print.html" title="Print this book" aria-label="Print this book">
                            <i id="print-button" class="fa fa-print"></i>
                        </a>
                        
                        
                    </div>
                </div>

                
                <div id="search-wrapper" class="hidden">
                    <form id="searchbar-outer" class="searchbar-outer">
                        <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
                    </form>
                    <div id="searchresults-outer" class="searchresults-outer hidden">
                        <div id="searchresults-header" class="searchresults-header"></div>
                        <ul id="searchresults">
                        </ul>
                    </div>
                </div>
                

                <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
                <script type="text/javascript">
                    document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
                    document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
                    Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
                        link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
                    });
                </script>

                <div id="content" class="content">
                    <main>
                        <h1 id="create-read-update-delete"><a class="header" href="#create-read-update-delete">Create, Read, Update, Delete</a></h1>
<p>When you have your <a href="./Schema.html">Schema</a> and <a href="./Model.html">Models</a> defined, learn how to manipulate them!</p>
<h2 id="collections"><a class="header" href="#collections">Collections</a></h2>
<p>The <code>Collection</code> object is how you find, query, and create new records of a given type.</p>
<h4 id="get-a-collection"><a class="header" href="#get-a-collection">Get a collection</a></h4>
<pre><code class="language-js">const postsCollection = database.collections.get('posts')

// Shortcut syntax:
const postsCollection = database.get('posts')
</code></pre>
<p>Pass the <a href="./Schema.html">table name</a> as the argument.</p>
<h4 id="find-a-record-by-id"><a class="header" href="#find-a-record-by-id">Find a record (by ID)</a></h4>
<pre><code class="language-js">const post = await postsCollection.find('abcdef')
</code></pre>
<p><code>find()</code> returns a Promise. If the record cannot be found, the Promise will be rejected.</p>
<h4 id="query-records"><a class="header" href="#query-records">Query records</a></h4>
<p>Find a list of records matching given conditions using <code>.query()</code>:</p>
<pre><code class="language-js">const allPosts = await postsCollection.query().fetch()
const starredPosts = await postsCollection.query(Q.where('is_starred', true)).fetch()
</code></pre>
<p><strong>➡️ Learn more:</strong> <a href="./Query.html">Queries</a></p>
<h2 id="modifying-the-database"><a class="header" href="#modifying-the-database">Modifying the database</a></h2>
<p>To create, update, or delete records, use the respective operations <strong>wrapped in an Action</strong>:</p>
<pre><code class="language-js">await database.action(async () =&gt; {
  const post = await postsCollection.find('abcdef')
  await post.update( /* update the post */ )
  await post.markAsDeleted()
})
</code></pre>
<p><strong>➡️ Learn more:</strong> <a href="./Actions.html">Actions</a></p>
<h3 id="create-a-new-record"><a class="header" href="#create-a-new-record">Create a new record</a></h3>
<pre><code class="language-js">await database.action(async () =&gt; {
  const newPost = await postsCollection.create(post =&gt; {
    post.title = 'New post'
    post.body = 'Lorem ipsum...'
  })
})
</code></pre>
<p><code>.create()</code> takes a &quot;builder function&quot;. In the example above, the builder will get a <code>Post</code> object as an argument. Use this object to set values for <a href="./Model.html">fields you defined</a>.</p>
<p><strong>Note:</strong> Always <code>await</code> the Promise returned by <code>create</code> before you access the created record.</p>
<p><strong>Note:</strong> You can only use field setters in <code>create()</code> or <code>update()</code> builder functions.</p>
<h3 id="update-a-record"><a class="header" href="#update-a-record">Update a record</a></h3>
<pre><code class="language-js">await database.action(async () =&gt; {
  await somePost.update(post =&gt; {
    post.title = 'Updated title'
  })
})
</code></pre>
<p>Like creating, updating takes a builder function, where you can use field setters.</p>
<p><strong>Note:</strong> Always <code>await</code> the Promise returned by <code>update</code> before you access the modified record.</p>
<h3 id="delete-a-record"><a class="header" href="#delete-a-record">Delete a record</a></h3>
<p>There are two ways of deleting records: syncable (mark as deleted), and permanent.</p>
<p>If you only use Watermelon as a local database, destroy records permanently, if you <a href="./Advanced/Sync.html">synchronize</a>, mark as deleted instead.</p>
<pre><code class="language-js">await database.action(async () =&gt; {
  await somePost.markAsDeleted() // syncable
  await somePost.destroyPermanently() // permanent
})
</code></pre>
<p><strong>Note:</strong> Don't access, update, or observe records after they're destroyed.</p>
<h2 id="advanced"><a class="header" href="#advanced">Advanced</a></h2>
<ul>
<li><code>Model.observe()</code> - usually you only use this <a href="./Components.html">when connecting records to components</a>, but you can manually observe a record outside of React components. The returned <a href="https://github.com/reactivex/rxjs">RxJS</a> <code>Observable</code> will emit the record immediately upon subscription, and then every time the record is updated. If the record is deleted, the Observable will complete.</li>
<li><code>Query.observe()</code>, <code>Relation.observe()</code> — analagous to the above, but for <a href="./Query.html">Queries</a> and <a href="./Relation.html">Relations</a></li>
<li><code>Query.observeWithColumns()</code> - used for <a href="./Components.html">sorted lists</a></li>
<li><code>Collection.findAndObserve(id)</code> — same as using <code>.find(id)</code> and then calling <code>record.observe()</code></li>
<li><code>Model.prepareUpdate()</code>, <code>Collection.prepareCreate</code>, <code>Database.batch</code> — used for <a href="./Actions.html">batch updates</a></li>
<li><code>Database.unsafeResetDatabase()</code> destroys the whole database - <a href="https://github.com/Nozbe/WatermelonDB/blob/22188ee5b6e3af08e48e8af52d14e0d90db72925/src/Database/index.js#L131">be sure to see this comment before using it</a></li>
<li>To override the <code>record.id</code> during the creation, e.g. to sync with a remote database, you can do it by <code>record._raw</code> property. Be aware that the <code>id</code> must be of type <code>string</code>.</li>
</ul>
<pre><code class="language-js">await postsCollection.create(post =&gt; {
  post._raw.id = serverId
})
</code></pre>
<hr />
<h2 id="next-steps"><a class="header" href="#next-steps">Next steps</a></h2>
<p>➡️ Now that you can create and update records, <a href="./Components.html"><strong>connect them to React components</strong></a></p>

                    </main>

                    <nav class="nav-wrapper" aria-label="Page navigation">
                        <!-- Mobile navigation buttons -->
                        
                            <a rel="prev" href="Model.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                                <i class="fa fa-angle-left"></i>
                            </a>
                        

                        
                            <a rel="next" href="Components.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                                <i class="fa fa-angle-right"></i>
                            </a>
                        

                        <div style="clear: both"></div>
                    </nav>
                </div>
            </div>

            <nav class="nav-wide-wrapper" aria-label="Page navigation">
                
                    <a rel="prev" href="Model.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
                        <i class="fa fa-angle-left"></i>
                    </a>
                

                
                    <a rel="next" href="Components.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
                        <i class="fa fa-angle-right"></i>
                    </a>
                
            </nav>

        </div>

        

        

        

        
        <script type="text/javascript">
            window.playground_copyable = true;
        </script>
        

        

        
        <script src="elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
        <script src="mark.min.js" type="text/javascript" charset="utf-8"></script>
        <script src="searcher.js" type="text/javascript" charset="utf-8"></script>
        

        <script src="clipboard.min.js" type="text/javascript" charset="utf-8"></script>
        <script src="highlight.js" type="text/javascript" charset="utf-8"></script>
        <script src="book.js" type="text/javascript" charset="utf-8"></script>

        <!-- Custom JS scripts -->
        

        

    </body>
</html>
